The correct option is
B secondary and tertiary consumers
A. Primary consumers are the herbivores which feed directly on producers and vary according to the type of ecosystem.
B. Secondary consumers are carnivores which feed on primary consumers and tertiary consumers are top carnivores that feed on other carnivores.
C. Reducers are decomposers that convert organic dead remains into simple inorganic substances.
D. Zooplanktons are microscopic organisms found in oceans and freshwater bodies.
So, the correct answer is 'secondary and tertiary consumers'.